How to handle changing goals in a DQN?
The simplest thing you can do is to add data regarding the target pose to the state vector. This will allow any generalisations that the agent learns that apply to similar poses to be used directly.
Clearly in normal use, where the target pose remains fixed during the episode, then that part of the state information will not change either during the episode. You will also need to train with a large variety of target poses - so training will take longer.
Multi-Objective Deep Reinforcement Learning is slightly different in that it attempts to resolve prioritising between multiple sub-goals. It would also be a more complex solution, whilst augmenting the state vector should allow you to continue using a very similar DQN set up as you have already.